Recently, electronic devices, such as smartphones and tablet terminals, have become widely used, and there has been an increasing demand to reduce failure rates. Some of the failures are bad contacts caused by rust and oxide films that are formed in terminal insertion portions such as switches and earphone jacks in electronic circuits.
As one technique for restraining bad contacts, for example, there is known a technique in which, at the time of turning on a switch, a current in the form of pulses is supplied to the switch to break an oxide film generated at a contact of the switch, so that a bad contact state of the switch contact is avoided. There is known another technique in which, at the time of connecting a terminal to a terminal insertion portion, rust is removed by rotating the terminal, so that a bad contact of the terminal is avoided. These techniques are disclosed in Japanese Laid-open Patent Publication No. 2011-230652, Japanese Laid-open Patent Publication No. 2000-182685, and Japanese Laid-open Patent Publication No. 6-096637.